Fractal model for permeability estimation in low-permeable porous media with variable pore sizes and unevenly adsorbed water lay

Dai, Quanqi; Wang, Guiwen; Zhao, Xiaoliang; Han, Zongyan; Kai, Lu; Lai, Jin; Wang, Song; Liu, Dong; Li, Yafeng; Wu, Kunyu

doi:10.1016/j.marpetgeo.2021.105135

Cited by 20 publications

(15 citation statements)

References 72 publications

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“…After centrifugal, there is only irreducible water in the rocks, so the corresponding T 2 spectrum can reflect the pore size distribution of irreducible fluid space. Generally, T 2 cutoff (T 2C ) is a relaxation time threshold that divides the total pore space into irreducible fluid space and the movable fluid space, whereas to the left of T 2C is irreducible water, and to the right of T 2C is movable water [6,30,42,43]. However, it should be noted that the centrifuged curve is not zero even to the right of the T 2C ðT 2 > T 2C Þ (Figure 1), implying that some portions considered movable water traditionally in the larger pores are not effectively movable [7,44].…”

Section: Nmr T 2 Spectra Of Movable Fluid Space and Total Porementioning

confidence: 99%

“…In addition, the contents of carbonate minerals have slight negative correlations with the ½αðxÞ 0 -αðxÞ max and ½αðyÞ 0 -αðyÞ max (Figures 8(e) and 8(f)), which means the carbonate minerals are also conducive to the formation of a good pore structure but with less effect on the pore structure compared with the (quartz+feldspar) minerals. This may depend on whether the intercrystalline carbonate pores are filled with the clay minerals or protected by the quartz and feldspar minerals during the diagenesis of the E 3 2 shales [43,48], while the real reason needs to be further explored.…”

Section: Effects Of Shale Compositions On Multifractal Parametersmentioning

confidence: 99%

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Evaluating Pore Structure of Shale Reservoirs through Pore Space Multifractal Characterization

Dai

Dong

et al. 2023

Geofluids

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Characteristics of pore structure are crucial to oil exploration and development in shale reservoirs, but practical evaluation of shale pore structure remains a longstanding challenge. In this study, based on nuclear magnetic resonance transverse relaxation time (T2) spectra under water-saturated and irreducible conditions, total pore space and moveable fluid space were skillfully determined. Meanwhile, multifractal spectra were used to characterize T2 distributions of total pore space and movable fluid space. The results show characteristic parameters of high probability measure areas of multifractal spectra (multifractal parameters) have strong negative correlations with T2 geometric mean value, and average radii of pore and throat increase with a decrease in the multifractal parameters, indicating the shale reservoirs with low values of the multifractal parameters may have good pore structure. Moreover, clay mineral content has strong positive effects on the multifractal parameters. In contrast, (quartz+feldspar) mineral content negatively influences on the multifractal parameters. Finally, new accurate models for permeability estimation in core scale and well-logging scale of shales are both proposed based on the multifractal parameters, which are also applicable for the other reservoirs. Overall, this study is important and timely for evaluating pore structure and predicting permeability in shale reservoirs.

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Section: Nmr T 2 Spectra Of Movable Fluid Space and Total Porementioning

confidence: 99%

Section: Effects Of Shale Compositions On Multifractal Parametersmentioning

confidence: 99%

Evaluating Pore Structure of Shale Reservoirs through Pore Space Multifractal Characterization

Dai

Dong

et al. 2023

Geofluids

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“…Du et al developed a mathematical model based on fractal theory to predict the permeability of natural gas hydrates and validated the proposed model using published experimental data. Dai et al further proposed a fractal permeability model with variable pore size by considering pore connectivity and water adsorption. These studies effectively establish quantitative expressions between permeability and pore microstructure parameters, which provide a good reference for the application of fractal theory to seepage in rocks.…”

Section: Introductionmentioning

confidence: 99%

Stress-Dependent Fractal Model for Predicting the Relative Permeability of Rocks Based on Equivalent Capillaries

Kong,

Zhao,

Teng

et al. 2023

Ind. Eng. Chem. Res.

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“…However, the high complex and irregular geometry features have been ignored [31][32][33][34]. Many scholars have simulated cement and rock internal pore structures based on a fractal model; pore structure characteristics can be described by fractal parameters such as fractal dimensions of the pore surface, pore tortuosity, and fracture surface [35][36][37][38][39][40]. The studies provide a theoretical background to the proposed functional relationships between fractal dimensions and basic macro properties.…”

Section: Introductionmentioning

confidence: 99%

Investigation on Pore Structure and Permeability of Concrete–Rock Interfacial Transition Zones Based on Fractal Theory

et al. 2022

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The concrete–rock interfacial transition zone (ITZ) is generally considered the weak layer in hydraulic engineering, for it is more permeable than the intact concrete or rocks. The water permeability of the ITZ is a critical parameter concerned with structural safety and durability. However, the permeability and pore structure of the ITZ has not been investigated previously, and the mathematical model of ITZ permeability has not been established. This study performed multi-scale experiments on the concrete–rock ITZ with various rock types (limestone, granite, and sandstone). A series of quantitative and qualitative analysis techniques, including NMR, SEM-EDS, and XRD, characterize the ITZ pore structures. The controlled constant flow method was used to determine the permeability of the concrete, rock, and ITZ. The mathematical model of ITZ permeability was proposed using the fractal theory. The consistency between the experimental data and the proposed model indicates the reliability of this study. The results of the experiment show that ITZ permeability is between 4.08 × 10−18 m2 and 5.74 × 10−18 m2. The results of the experiment and the proposed model could determine ITZ permeability in hydraulic structure safety and durability analysis.

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Fractal model for permeability estimation in low-permeable porous media with variable pore sizes and unevenly adsorbed water lay

Cited by 20 publications

References 72 publications

Evaluating Pore Structure of Shale Reservoirs through Pore Space Multifractal Characterization

Evaluating Pore Structure of Shale Reservoirs through Pore Space Multifractal Characterization

Stress-Dependent Fractal Model for Predicting the Relative Permeability of Rocks Based on Equivalent Capillaries

Investigation on Pore Structure and Permeability of Concrete–Rock Interfacial Transition Zones Based on Fractal Theory

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